un souhaitable derrière (A Desirable Behind)
by an-alternate-world
Summary: GKM Fill (AU). Sebastian's first words had shown he had a thing for Blaine's ass. A series of snapshots where Sebastian's obsession is clear.


**Title: **un souhaitable derrière (A Desirable Behind)  
><strong>Author: <strong>an-alternate-world  
><strong>Rating:<strong> M+  
><strong>CharactersPairing: **Blaine Anderson/Sebastian Smythe  
><strong>Word Count:<strong> 3,761  
><strong>Summary:<strong> GKM Fill (AU). Sebastian's first words had shown he had a thing for Blaine's ass. A series of snapshots where Sebastian's obsession is clear.  
><strong>WarningsSpoilers:** Some filthy language from Seb. Sex scenes. Mild kinks (blindfolds, spanking).  
><strong>Disclaimer:<strong> I am in no way associated with Glee, FOX, Ryan Murphy or anything else related to the FOX universe.

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><p><em>Many thanks to Rum (rrrumbleroar) for beta reading this ages and ages ago.<em>

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><p>Blaine had never forgotten Sebastian's first words to him.<p>

"Well, hello there. You have an ass I'd like to fuck."

He'd been mortified and nearly thrown his drink at the smirking man with his hands tucked carefully into his front pockets, but then he'd noticed the sparkle in his eyes and the line of freckles down his neck and taken a cautious sip instead. It had been a good opportunity to size the man up, biding his time and making them both wait.

"And what makes you think I'd let you anywhere near it?"

The mystery man had stepped closer, crowding into Blaine's space. The difference in heights had made Blaine feel dizzy when air had gotten caught in his lungs. He'd strained his neck to look up and became conscious of the warmth emanating from the man's chest against his. Ordinarily he might feel threatened, but instead he just felt an urge to find the nearest flat surface and hand himself over to this man.

"Because you'll never want another dick in it after my talent has claimed it."

It was so absurd and crude that Blaine had scoffed and turned away, leaving his drink behind so he could lose himself in the crowd of dancers. Hands brushed against his chest, his back, his legs, tantalisingly warm and yet leaving him constantly unfulfilled. He spent the night feeling like he was being watched and any time he dared to chance a look, he found the same set of sparkling eyes on him from the bar.

As the evening wore on, he had a few too many drinks, got a little too tipsy, and so when foreign hands slid to his hips, pulling his ass into an obvious bulge, he moaned and let himself be led to the beat of the music. Bodies continued to surround them, a writhing mass of limbs and sweat that quickly had Blaine getting aroused. This was more than just being tantalised.

"I'd still like to fuck that ass of yours," he heard whispered into his ear. He stiffened at the words, knowing instantly who they belonged to. A mouth nipped at his neck, a hand rubbed against his crotch until it located the outline of his cock. He allowed the stranger to rub him off until he was staining his underwear and he was pretty sure he had a hickey on the side of his neck because it was tingling when the man's lips moved away.

"Wait!" He grabbed at the shirt before the man disappeared. The stranger had paused, looking down at him with an amused grin. "I'm drunk. Take me home."

The man had continued to stare, green eyes flickering over Blaine's body before he'd nodded, agreed, and helped him through the streets until Blaine was safely inside his apartment and stripped down to nothing. It had made the stranger hard again, seeing him so exposed, but he wasn't going to do more with this stranger when he was too intoxicated and would possibly regret it after he woke up.

The following morning, he'd found a scribbled name and phone number on his kitchen counter. Blaine had never confessed to how he still had that piece of paper tucked into a hidden pocket in his wallet.

On bad days, reading "_(I'm the guy who wants to fuck your ass)_" beneath "_Sebastian_" made him smile like a loon.

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><p>Their relationship had never been conventional, but as Sebastian liked to say, conventional was for boring people and neither of them were boring. The handjob was the only intimacy they shared for six months as Blaine tried to negotiate Sebastian's innuendos and flirting. Almost every comment Blaine made was twisted around until it came back to Sebastian's obsession with his ass, and sometimes Blaine deliberately wore his tightest pants just to see the reaction it would get from Sebastian as he approached the male in the street for coffee.<p>

He never failed to be amused by the way Sebastian's eyes widened and darkened, his pink lips parting just a little. The best days were those that he could tell Sebastian was half-hard when he walked away.

Eventually Sebastian turned more…demanding, Blaine supposed. Aggressive gave entirely the wrong impression. Sebastian was always very respectful of the boundaries Blaine had, apologising as sincerely as possible when Blaine indicated he'd pushed too far. Yet he continued to try pushing those boundaries, sliding his hands into the back pocket of Blaine's pants frequently, squeezing through the fabric even if they were standing in line at a busy coffee shop. He had absolutely no shame in repeatedly watching Blaine's ass, of chatting about it as easily as he did the weather or a change in the stock market.

What was most challenging to deal with was Sebastian's lack of embarrassment in expressing exactly what he wanted. Sebastian wasn't what Blaine would call arrogant, but his easy confidence made Blaine more acutely aware of his discomfort. Not that he'd blame Sebastian for being uncomfortable. Blaine had never learned to truly own his body with pride, to understand his own skin an accept it. He knew men admired him and he thrilled in flirting with them, but he was often oblivious to the signs of them wanting _more_. Sebastian removed that confusion by being utterly blatant about his intentions, twisting everything inside him into knots until he was a blushing mess of shy smiles and lowered eyes.

Sebastian said he found the bashful schoolboy thing hot, his eyes sparkly and his grin wide. Blaine just found it mortifying that nothing he did dissuaded Sebastian's focus on bedding him – even though he was secretly grateful and kept trying to ignore his heart skipping beats every time Sebastian smiled a certain way.

After six months of hanging out multiple times a week for coffee and dinner dates, Sebastian had begun to give up on pressing his hand to Blaine's ass every time he got the chance. Instead, he'd chosen to push Blaine against his door, kissing him hard enough to make his lips ache and his knees tremble. The fact they were still in the corridor of Sebastian's apartment block barely crossed either of their minds as Sebastian's kiss softened from insistent to hesitant, before he finally, finally pulled completely away.

"Sorry. I shouldn't have done that. You just… God, you make it so hard sometimes."

"I've noticed," Blaine said, quirking his eyebrows as he looked down where he could see the slight curve within Sebastian's jeans, fiddled with Sebastian's buttons between trembling fingers, bit at his swollen lower lip nervously. "Should we go inside?"

Sebastian had dropped his keys in shock before nearly breaking his front door key in his haste to unlock the door. Their shoes clattered to the floor, followed by half-rolled socks and inside-out coats. A trail of clothes was left on the path to Sebastian's bed with a few scattered buttons and ripped stitches possible casualties to their abundance of haste and lack of attention.

When Sebastian was finally straddled above Blaine, flushed and hard and sweaty, he'd grinned. "_Beautiful_," he said and Blaine, being Blaine, had felt his cheeks bloom with heat.

He'd let Sebastian do as they had both so desperately wanted for months. He'd clutched Sebastian's hair when the man had sucked his cock, had whined his name when Sebastian's lips had closed around his balls, had writhed and moaned when Sebastian had fucked his hole with his tongue. He was barely coherent when Sebastian had flipped him over, the hard length rubbing against the back of his thigh.

"Can I fuck that ass of yours yet?"

Blaine had barely been capable of nodding, his heart thumping out of his chest. Sebastian quickly found lube and began to stretch him, babbling incessantly about the various qualities of his ass. Blaine wasn't sure he'd ever heard Sebastian babble but it wasn't something he was willing to stop because he was lost to the feeling of long, confident fingers scissoring inside him. On his hands and knees with his ass out and exposed, he knew he'd been shaking when Sebastian had entered him for the first time.

"_Fuck_, Blaine," Sebastian gasped, thrusting into him until Blaine could barely hold himself up with the intensity of each movement. Long fingers had gripped his cock, jerking him off until he was coming with a broken cry and uncontrolled spasms of his muscles. Behind him, Sebastian had grunted and filled the condom.

They laid together afterwards, exchanging kisses and touches, lazy and warm. Sebastian's hands kept curving over his ass and squeezing it, rubbing his middle finger against Blaine's stretched rim.

"Beautiful," he murmured again, and Blaine hadn't blushed so much that time.

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><p>They hadn't made their relationship official for a while, but Blaine suspected everyone knew before they'd had sex that they were in a relationship. Sebastian had always been ridiculously open to groping his ass in public and whispering filthy things into his ear about what he'd like to do if they were alone. If Blaine had thought it was a challenge to remain calm and unaroused before, it got worse after they were "together". Now, Sebastian felt he had an actual <em>right<em> to say such things and Blaine was too breathless and turned on to want to stop him.

Sebastian took him to a seedy club once, fucking him inside a toilet cubicle while growling about how everyone would be jealous of what Sebastian, and Sebastian alone, got to take. Blaine's come had splattered against the wall of the cubicle and Sebastian had marked up the back of his neck with hickeys which were impossible to cover up at work after the weekend had ended.

He quickly discovered it was impossible to take Sebastian with him when he went clothes shopping. Any time he emerged from the change room, Sebastian's eyes would darken as he demanded Blaine turn around to assess his ass. Even if he was only trying on shirts or bow ties, Sebastian would be fixated on his behind. There had been one time, when he'd been rather desperate for Sebastian's approval for an outfit, that his boyfriend had instead crowded him into the change room and blown him, squeezing his ass tight between two hands. Blaine had barely been able to look the shopgirl in the eyes as he'd hurried out of the store afterwards, pretty sure that she'd heard the barely stifled gasp when he'd come down Sebastian's throat.

In Sebastian's defence, he was always capable of turning the most boring of things interesting. Sometimes he was pulled into Sebastian's lap at parties, allowing Blaine to feel Sebastian's erection as well as conceal it from their curious friends.

"Feel that? All because of those pants you're wearing. I'll fuck that pretty ass raw when we get back to your place later."

He'd learned Sebastian was nothing if not a man of his word.

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><p>They'd been together for nearly a year when Sebastian added a new element. He wrapped a blindfold around Blaine's eyes when he'd been propped up on his hands and knees. The fingers he knew so well were light but practised as they explored Blaine's most sensitive places, drawing whimpers and moans from his throat because everything felt like so much <em>more<em> when he couldn't see. He'd been stretched until he expected Sebastian to enter him, his cock hard and untouched between his legs.

The smack was sudden, painful, completely unexpected. He cried out in surprise then wrinkled his brow when Sebastian's hand soothed the sting.

"You need to be punished for having an ass like this," Sebastian muttered, smacking him again on the opposite cheek. Whatever it was felt harder than Sebastian's palm, like a piece of wood. "It's just too distracting. Do you know how often I get hard at work when I start thinking about fucking you? Do you know how often I wake up before you and have to force myself not to fuck you while you sleep?"

Blaine moaned as Sebastian talked and rained down spankings on his ass, his cock throbbing between his legs as the pain of being smacked began to transform into pleasure.

"You like it, don't you? You _like_ knowing I'm obsessed with your ass." Whatever it was which Sebastian was wielding left the fleshy sit-spot of his ass burning and tingling, leaving him teetering on the edge of his orgasm.

And he hadn't even been touched yet.

"Fuck, you're hot."

Sebastian's cock pushed into his ass, hard and fast, and he clutched at the sheets as the pleasure of being taken combined with the feeling of Sebastian's skin against the bruising on his ass. The thrusts bordered on brutally harsh, enough to make him know he would hurt tomorrow from more than just the spanking. He arched into each flitting touch of Sebastian's hands, broken pleas passing his lips as pleasure spiralled within him.

He came without his cock being touched, before he truly expected to, collapsing against his hands as shudders wracked his body. Sebastian praised him and cursed him in the same sentence, his rhythm erratic as he fell over the edge.

The blindfold was removed. He blinked repeatedly until his eyes adjusted to the change in light and he saw the paddle thing near the edge of the bed. It looked like something you would play table tennis with, and he wasn't sure he'd ever be able to play again without flushing. His ass still smarted but Sebastian lavished kisses and licks to the bruising until the hurt had dissipated. With a satisfied hum, he cuddled into Sebastian's broad chest and fell asleep.

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><p>They were at some fancy function thing for Sebastian's work and Blaine has been holding the same glass of wine for the past hour. He'd barely touched it, hardly dared, because he knew that this was an important event for Sebastian and the last thing either of them needed was him making a drunken fool of himself in front of impressionable colleagues. Instead, he alternated between being pressed into Sebastian's side and drifting away to chat with the wives of men that Sebastian worked with, offering compliments to both beautiful and ugly dresses, discussing the latest music trends or must-read books.<p>

Several times, he'd had to carefully adjust Sebastian's hand to the small of his back. They had _tried_ to set careful limitations on the night before arriving.

Blaine wasn't to get drunk.

Sebastian wasn't to grope him.

It had all sounded so simple that it ought to be foolproof.

By the time the second hour was drawing to a close, he was so wound up with sexual frustration that he thought one of the wives was about ready to take pity on him. Sebastian had been eyeing him from across the room with a heat he was familiar with from that first encounter in a club. He'd unashamedly brushed past Blaine several times to pinch his butt, making Blaine jump and stutter in the middle of whatever conversation he was having. He knew that Sebastian was smart enough to gauge the effect it was having on him, and he wondered at what point it would be rude to beg away from the function just so his boyfriend could fuck him.

Sebastian politely interrupted a bland conversation with yet another woman Blaine had never met. Long fingers slipped between his own, leading him away to a quieter section by the wall.

"What happened to keeping your hands to yourself?" Blaine huffed, discarding his wine glass on a table so he could more effectively cross his arms over his chest and pout.

"Your ass happened," Sebastian pointed out, leaning into his space, towering over him. At first, the difference in height had annoyed Blaine. It was even more frustrating when Cooper had teased him for being such a squirt beside his boyfriend. Gradually, he'd grown to love the security of wrapping himself up in Sebastian's taller body, of being able to have Sebastian's cheek rest atop his head when they danced together slowly.

"And what am I meant to do about that particular problem? Cut it off?"

"You wouldn't dare," Sebastian murmured, leaning in to kiss Blaine's cheek as his green eyes swept over the people, searching for anyone who might pose a threat to two males exchanging affection. "Let's leave. I've been wanting to fuck you for _hours_."

Blaine's eyes fluttered shut when Sebastian's hands grasped at his waist to pull him closer. He could clearly feel the outline of Sebastian's half-hard cock pressing against his hip. His boyfriend's desires and intentions were clear. "Isn't it rude to just…leave?"

"It's rude that I can't concentrate because I'm imagining you bent over the kitchen table, so I'm totally useless here."

Blaine rolled his eyes as Sebastian kissed his forehead, the gentle touches forever at odds with the filth that poured from his mouth. To anyone watching them, they probably looked cute, couple-y and close, rather than bordering on uncontainable sex fiends. He gave up trying to find possible arguments and allowed Sebastian to tow him around, saying farewells before they scurried away together. Sebastian had already begun palming Blaine in the taxi before he'd managed to tell the driver where to go.

He squirmed in the backseat, struggling to keep his noises to himself, knowing how much Sebastian liked making him vocalise every moment of pleasure. He was pretty sure the driver had an idea of what was happening but, as usual, Sebastian had no shame in exhibitionism, in bringing him to the edge of embarrassment.

It meant that Sebastian pulling away was a blessing and a curse.

He was shaking with need, clinging to his thigh and Sebastian's wrist until they arrived at their apartment.

Sebastian threw money at the driver, too much even with a tip but neither of them were willing to wait for change as Sebastian hurried them to the elevator. The doors had barely closed before his boyfriend was pushing him against the wall, hands gripping his ass tightly, mouthing at his neck.

"There should be a law against you having this," Sebastian muttered, rutting against Blaine's thigh as the elevator crawled towards their floor.

"There should be a law against you having hands and eyes," Blaine complained, his voice mild as he flushed. Anything further he wanted to say was cut off by Sebastian's tongue sliding into his mouth. It didn't matter that the elevator could stop at any time and anyone could see them. He let Sebastian feel him up, kiss him senseless, because his hormones were racing and his body thrummed with heat.

They stumbled through the door to their apartment, kicking away shoes and tossing jackets to the floor. Belts clattered to the tiles and pants and underwear swished to the floor. Sebastian scooped him up to deposit him on the bed and he didn't stop himself from rolling onto his stomach, presenting his ass to Sebastian's waiting hands and moaning when the first slick finger plunged into him.

"You need to wear skirts," Sebastian said, quickly working up to a second finger as he unbuttoned his shirt with his spare hand. "Skirts and no underwear, because it makes access _so_ quick when I can't bear it anymore."

Blaine rocked against the fingers, whining until Sebastian added a third. He pulled at his shirt until it was finally off, his body rubbing repeatedly into the bed, his cock dragging against the cotton sheets.

"You're always so willing, aren't you? You'd probably love me to lift up a skirt and slide straight into you." Sebastian twisted his fingers, making Blaine buck against the bed, and then removed them. "_Fuck_, I love your ass."

Blaine groaned as Sebastian rolled into him, the pace lacking any sort of gentleness as he was driven into the mattress. Sebastian rubbed the back of his thighs and the flesh of his ass, sinking into him over and over until Blaine was gasping, trembling, shuddering.

"Let go, babe. Come around my cock."

Sebastian angled his body to pinpoint Blaine's prostate, hammering it until Blaine was shattering apart and convulsing against the bed, feeling the heated come of his boyfriend within him as Sebastian came with a low moan.

"God, you feel so good," Sebastian murmured, kissing the back of his shoulder blades as he pulled out and rolled Blaine over, kissing his neck and jaw up to his lips. It was still filled with need and want, but a gentleness, a care, that he'd become accustomed to. A devilish smirk crossed Sebastian's lips as he kissed the corner of Blaine's mouth. "I told you that you had an ass I wanted to fuck."

Blaine laughed, stroking fingers down sweaty, freckled skin. "You also told me I'd never want to find another one because you had so much talent."

"And I was right, wasn't I?" Sebastian teased, tracing his fingers through the come that stained Blaine's stomach and licking at them with a satisfied hum. "No one else has fucked you the way I do."

Blaine had already admitted to himself that no one was like Sebastian. He didn't doubt that his boyfriend knew that too. It was in every look, every touch, every word. He hooked his ankles around Sebastian's legs and pulled him close, nuzzling kisses to his neck. "I love you, you know."

Sebastian smiled and kissed him, long and slow. His hand dipped between Blaine's legs to feel the come leaking from his hole, practically purring as he stroked inside with his fingertips. Blaine quivered beneath him, feeling like a trapped piece of prey, and yet Sebastian just looked happy, pleased, as content as Blaine felt. "I love you too, Killer."

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><p><strong>GKM Prompt:<strong>

_As canon has (oh so wonderfully) established, Sebastian totally has a thing for Blaine's ass. I'd love to see an established relationship fic where Sebastian is always all over Blaine in public always touching/squeezing/groping his ass and despite being a little embarrassed Blaine is totally turned on by it. And then when they have penetrative sex Sebastian is just all about Blaine's ass._

_And just lots of focus on the PDA parts, not just the sex._

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><p><em><strong>~FIN~<strong>_


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